In the prior art, the connectors connecting two line sections are of several kinds. The strength of the connection is generally improved by screwing of a nut onto a connection portion.
A known kind of connector uses mechanical “back to back” concept, shown in FIG. 1. In the “back to back” concept, the two connectors 98 to be connected together are similar, but there is an additional part 99, the “back to back” part, not belonging to one of the connectors and connected between them with each of them, as shown in the figure. Each of the connectors 98 comprises a connection part 100, exteriorly threaded, and a ring 101, or nut, interiorly threaded so as to be screwed to the connection part 100. The additional part 99 is substantially cylindrical and hollow so as to allow the passage of a portion of the connection parts 100 for carrying out the connection. The additional part 99 comprises, on its external surface, two circular grooves 102. Each ring 101 comprises on its internal surface a corresponding groove 103. The grooves 102 and 103 are to be put one in front of the other, then forming a circular tunnel for housing ball bearing, not shown in the figure.
A drawback of the presence of such additional part is that there are more interfaces between the connectors 98 and the additional part 99 than if there were only two connectors. This increases risks relative to the watertightness of the connection.
Moreover, during operation, said additional part 99 remains connected to one connector 98 which makes the connector 98 not reversible, thereby reducing the productivity of the operation.
Furthermore, as the additional part 99 “back to back” comprises ball bearing, which is likely to be in contact with the environment, in particular with moisture of the seabed. This may cause the jamming of the ball bearing.
Another drawback is that the stiff length of the connectors when connected is longer, due to the presence of the additional part 99. Indeed, when pulling on the cable for bringing it back on the vessel, bending stresses appears on the connector. The more the length of the connector is important, the more the value of these bending stresses is important due to the length of the connector acting like a lever arm.
Another known connector uses the mechanical “back to back” concept, with further an electrical insert. The drawbacks of said connector are similar to the previous one.
Two other known connectors are hermaphrodite, purely symmetrical, with thread locking, but said connectors are not adapted to shallow water operations under the sea level. Indeed, one of these connectors has a floating nut remaining once coupled, which risks to be damaged quite easily. Furthermore, the watertightness of this connector is linked to the screwing made by the operator, which is not secured. The other connector disclosed in FR2782197 has low watertightness and its nuts are too weak to handle marine operations.